Concrete floating docks and breakwaters, such as described in U.S. Pat. No. 4,318,361 to Sluys, are often assembled from a series of floating concrete modules. The modules typically comprise either a hollow concrete shell or a concrete shell surrounding a buoyant foam core. For use as a breakwater or a dock, the assemblage of modules are typically connected at one or both ends to an anchoring point, such as a driven piling or a weighted anchor. As a breakwater, the assemblage of modules is intended to absorb or reflect the incident wave energy and thereby provide a sheltered area of relatively calm water for the mooring of boats. When used as a dock, an assemblage of modules may be fitted with a suitable decking material, or the upper exposed concrete surface may be provided with a slip resistant finish.
Interconnection of the floating concrete modules for a dock or breakwater has been accomplished in a number of ways. For example, U.S. Pat. No. 4,693,631 to McKay discloses a pair of longitudinal strips running alongside and secured to the upper opposing sides of adjacent modules. In a similar fashion, U.S. Pat. No. 4,709,647to Rytand discloses opposing inner and outer sidewales, preferably formed of wood, for maintaining adjacent modules in alignment while leaving a one or two foot gap therebetween.
U.S. Pat. No. 3,091,203 to Usab discloses a floating dock with adjacent modules joined at an upper portion by an overhanging flange which thereby positions the lower portions of adjacent modules in spaced apart relation. The concrete modules also include tubular liners extending in only the upper portion of the modules to serve as channels for interconnecting cables. Thus, the interconnecting cables act only on the upper portions of the modules and the bottom portions of the modules are in spaced apart relation.
Unfortunately, interconnection of adjacent floatation modules in a floating dock or breakwater at only the top portion of the modules allows the modules to pivot relative to one another. Such pivotal movement places high stress forces on any interconnecting member and may subject such a member to premature failure. In addition, the pivoting motion provides a less effective inertial barrier to wave action and also creates an unstable surface for dock users. If the bottom portions of adjacent modules collide during the pivoting movement, damage to the modules at the point of collision is likely.
U.S. Pat. No. 4,321,882 to Sluys discloses chains or cables passing through two side-by-side passageways centrally located through a series of modules with a pair of resilient spacers positioned between adjacent modules. The modules are thus allowed to move pivotally with respect to one another. The pivotal movement of adjacent modules places considerable stress on the resilient spacers and may result in increased maintenance expense for repairing damaged or worn resilient spacers. The pivoting provides a less effective inertial barrier to the wave action and also may create an unstable surface for dock users. The pivoting action about a center point may damage both the top and bottom portions of adjacent modules when these portions collide as a result of wave action.